Search Results (22)

High-purity germanium (HPGe) gamma-ray detectors are core instruments in nuclear physics and astrophysics experiments, where long-term stability and reliable extraction of decay parameters are essential. However, the standard exponential decay analyses of the detector time-series data are often affected by the strong correlations between the fitted parameters and the sensitivity to detector-related fluctuations and outliers. In this study, we present a robust analysis framework for HPGe detector decay data based on pairwise ratios and the Steiner’s most frequent value (MFV) statistic. By forming point-to-point ratios of background-subtracted net counts, the dependence on the absolute detector response is eliminated, removing the amplitude–lifetime correlation that is inherent to conventional regression. The resulting pairwise lifetime estimates exhibit heavy-tailed behavior, which is efficiently summarized using the MFV, a robust estimator designed for such distributions. For the case study, a long and stable dataset from an HPGe detector was used. This data was gathered during a low-temperature nuclear physics experiment focused on observing the 216 keV gamma-ray line in ⁹⁷Ru. Using measurements spanning approximately 10 half-lives, we obtain a mean lifetime of $\tau =4.0959\pm 0.{0007}_{\mathrm{stat}}\pm 0.{0110}_{\mathrm{syst}}\mathrm{d}$, corresponding to a half-life of $T_{1/2}=2.8391\pm 0.{0005}_{\mathrm{stat}}\pm 0.{0076}_{\mathrm{syst}}\mathrm{d}$. These results demonstrate that the pairwise–MFV approach provides a robust and reproducible tool for analyzing long-duration HPGe detector data in nuclear physics and nuclear astrophysics experiments, particularly for precision decay measurements, detector-stability studies, and low-background monitoring. Full article

In recent years, polymer-based hybrid nanocomposites have emerged as promising alternatives to traditional heavy metal shields due to their low density, flexibility, and environmental safety. In this study, the synthesis of PS-PEG copolymers and the gamma radiation-shielding properties of PS-PEG/As₂O₃, PS-PEG/BN, and PS-PEG/As₂O₃/BN nanocomposites with different compositions are investigated. The goal is to find the optimal nanocomposite composition for gamma radiation shielding and dosimetry. Therefore, the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), effective atomic number, mean free path (MFP), radiation shielding efficiency (RPE), electron density, and specific gamma-ray constant were presented. Gamma rays emitted by the Eu source were detected by a high-purity germanium (HPGe) detector device. GammaVision was used to analyze the given data. Photon energy was in the vicinity of 121.8–1408.0 keV. The MAC values in XCOM simulation tools were used to compute. Gamma-shielding efficiency was increased by an increased number of NPs at a smaller photon energy. At 121.8 keV, the HVL of a composite with 70 wt% As₂O₃ NPs is 2.00 cm, which is comparable to the HVL of lead (0.56 cm) at the same energy level. Due to the increasing need for lightweight, flexible, and lead-free shielding materials, PS-b-PEG copolymer-based nanocomposites reinforced with arsenic oxide and BN NPs will be materials of significant interest for next-generation radiation protection applications. Full article

Multinuclide calibration sources, consisting of mixtures of gamma-emitting radionuclides, are commonly used for detector efficiency calibration in gamma-ray spectrometry. While they enable fast and accurate calibration, they have certain drawbacks, such as high cost and relatively short usable lifespans. This paper presents a simplified and cost-effective method for the efficiency calibration of cylindrical high-purity germanium (HPGe) detectors, which relies on the use of certified reference materials containing natural radionuclides. The method is based on selected gamma lines from natural radionuclides that are practically unaffected by the true coincidence summing (TCS) effect, enabling reasonably accurate calibration for multiple measurement geometries at energies above 200 keV. The main limitation of the method is its applicability only to energies higher than 200 keV; however, this range is sufficient for most routine environmental measurements. Verification measurements conducted for cylindrical geometry showed that detector efficiency values obtained using the proposed method (with IAEA RGK, RGU, and RGTh certified reference materials) differed by less than approximately 4% from those obtained using a commercial multinuclide calibration source. Full article

Gamma-ray analysis is a widely used technique for radioactive element characterization in environmental samples, contributing significantly to natural and anthropogenic radioactivity evaluations, particularly in areas such as natural reservations or regions that have been affected by nuclear pollutants. As the Danube Delta belongs to both categories, we decided to conduct a study in order to find out whether gamma spectroscopy is suited for pattern identification in common biota constituents such as reed and whether anthropogenic tracers can still be found in the samples. The answer to both questions is affirmative, as shown by the pattern and cluster analyses. Furthermore, our conclusions point out that it would be interesting to extend the spectroscopy and correlation studies to sediment and trophic chains over a certain period in order to obtain the transfer factors and information on radionuclide dynamics. The HPGe detector used proves this is the best class of sensing devices for such purposes. Full article

The concentration of natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in ceramic tiles manufactured in Poland is presented in this paper. The concentration of natural radioactive isotopes in the tested samples was determined using a low-level digital gamma ray spectrometer equipped with an HPGe semiconductor detector. The mean concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the analyzed samples were found to be 48 ± 3 Bq∙kg⁻¹, 49 ± 3 Bq∙kg⁻¹ and 476 ± 23 Bq∙kg⁻¹, respectively. The world mean concentrations of these radionuclides (50 Bq·kg⁻¹, 50 Bq·kg⁻¹ and 500 Bq·kg⁻¹, respectively) were not exceeded. Furthermore, in order to ascertain the level of gamma radiation exposure, fundamental radiation protection parameters were established: radioactivity concentration indicator/gamma ray indicator (I_γ), indoor dose rate (D_in) and annual indoor effective dose (E_in). In the case of the investigated ceramic tiles, it was established that the parameters were not higher than the limit values, except the indoor gamma radiation dose rate which was found to be 1.5 times higher than the world average. Therefore, the findings of this study indicate that the utilization of the examined ceramic tiles in constructions should be approached with a degree of caution. Full article

Ionizing radiation plays an essential role across various fields but also poses significant health risks, requiring effective shielding solutions. This study focuses on the photon shielding properties of PbO-reinforced composites, specifically PbO-0, PbO-2, PbO-4, PbO-6, PbO-8, and PbO-10, through experimental measurements of photon energies ranging from 59.5 keV to 1408.0 keV. The measurements were taken using an HPGe detector. Experimental results were compared to theoretical calculations. Among the tested composites, PbO-10, which contains the highest concentration of lead oxide (PbO), provided the most effective radiation shielding. This sample demonstrated superior mass and linear attenuation coefficients, offering excellent protection at low photon energies. Furthermore, PbO-10 exhibited the lowest half-value layer (HVL) and tenth-value layer (TVL) values, indicating its efficiency in reducing radiation intensity with thinner material layers. It was determined that the experimental TVL results for PbO-O, PbO-2, PbO-4, PbO-6, PbO-8, and PbO-10 at 59.5 keV photon energy were 9.95, 5.98, 4.77, 3.67, 3.22, and 2.71 cm, respectively. With these outstanding attenuation capabilities, PbO-10 is deemed highly suitable for use in medical, industrial, and radiation-heavy environments. In summary, this research emphasizes the effectiveness of PbO-reinforced composites in gamma-ray shielding, with PbO-10 emerging as the top performer, demonstrating great potential for applications that require durable and efficient radiation protection. Full article

In this work, we studied the effect of bismuth oxide particle size and its attenuation capacity as a filler additive in epoxy resins. Six samples were prepared according to the amount of microparticles and nanoparticles in the sample and were coded as ERB-1, ERB-2, ERB-3, ERB-4, ERB-5, and ERB-6. One of the composite epoxies contained Bi₂O₃ microparticles at a 50:50 ratio (ERB-6) and was chosen as the control composite, and the number of microparticles (MPs) was gradually decreased and replaced by nanoparticles (NPs) to produce epoxy-containing Bi₂O₃ nanoparticles at a 50:50 ratio (ERB-1). The morphological and thermal characteristics of the studied composites were tested. The attenuation capability of the prepared composites, which is determined by the Bi₂O₃ particle size, was determined experimentally using a semiconductor detector, an HPGe-detector, and three different gamma-ray point sources (Am-241, Co-60, and Cs-137). The linear attenuation coefficient (LAC) of ERB-3, which contained 30% nanoparticles and 20% microparticles, had the highest value compared to the other composites at all the energies discussed, while the ERB-6 composite had the lowest value at all energies. The radiation-shielding efficiency (RSE) of the prepared samples was determined at all discussed energies; at 662 keV, the radiation-shielding efficiency values were 15.97%, 13.94%, and 12.55% for ERB-3, ERB-1, and ERB-6, respectively. The statistics also proved that the attenuation capacities of the samples containing a combination of nanoparticles and microparticles were much superior to those of the samples containing only microparticles or nanoparticles. A ranking of the samples based on their attenuation capacity is as follows: ERB-3 > ERB-4 > ERB-2 > ERB-1 > ERB-5 > ERB-6. Full article

Gamma-ray spectroscopy is an effective technique for radioactive material characterization, routine inventory verification, nuclear safeguards, health physics, and source search scenarios. Gamma-ray spectrometers typically cannot be operated in the immediate vicinity of nuclear reactors due to their high flux fields and their resulting inability to resolve individual pulses. Low-power reactor facilities offer the possibility to study reactor gamma-ray fields, a domain of experiments hitherto poorly explored. In this work, we present gamma-ray spectroscopy experiments performed with various detectors in two reactors: The EPFL zero-power research reactor CROCUS, and the neutron beam facility at the Ohio State University Research Reactor (OSURR). We employed inorganic scintillators (CeBr₃), organic scintillators (trans-stilbene and organic glass), and high-purity germanium semiconductors (HPGe) to cover a range of typical—and new—instruments used in gamma-ray spectroscopy. The aim of this study is to provide a guideline for reactor users regarding detector performance, observed responses, and therefore available information in the reactor photon fields up to 2 MeV. The results indicate several future prospects, such as the online (at criticality) monitoring of fission products (like Xe, I, and La), dual-particle sensitive experiments, and code validation opportunities. Full article

In the present work, photon and neutron attenuation properties of polyepoxide composites produced by doping waste iron filings (IF) at different percentages (0%, 20%, 40%, and 60% iron filing percentage) were obtained using theoretical and experimental techniques. The experimental technique was performed using an HPGe detector with four different gamma lines (0.0595, 0.6617, 1.173, and 1.333 MeV) emitted from three gamma-ray sources (²⁴¹Am, ¹³⁷Cs, and ⁶⁰Co). The theoretical techniques for shielding parameters calculation are estimated with Phy-X software and the XCOM program as well. The experimental and theoretical values of the mass/linear attenuation coefficient (M/LAC), half/tenth value layer (H/TVL), mean free path (MFP), lead equivalent thickness (LEth), and radiation shielding efficiency (RSE) have been determined and compared. A good agreement was achieved during the comparison. The shielding performance of the prepared composites increased with increasing the iron filing rate, where we can arrange the performance of shielding according to EP–IF60 > EP–IF40 > EP–IF20 > EP–IF0 at all different experimental and theoretical energies. The effective and equivalent (Zeff, Zeq) atomic numbers as well as the exposure buildup factor (EBF) at different depletion distances or mean free paths (MFPs) have been calculated for all EP–IF composites. The lowest EBF was for EP–IF60 while the highest EBF was for EP–IF0 through the discussed energy from 0.015 to 15 MeV. Finally, the fast neutron removal cross-section (FRNC) has been calculated for the prepared composites and the results showed improvement in FNRC with increasing the iron filing rate. Full article

This study aims to explore the radiation protection properties of white mortars based on white cement as a binder and Bi₂O₃ micro and nanoparticles in proportions of 15 and 30% by weight as replacement sand. The average particle size of micro- and nano-Bi₂O₃ was measured using a transmission electron microscope (TEM). The cross-sectional morphology and distribution of Bi₂O3 within the samples can be obtained by scanning electron microscopy (SEM), showing that nanoscale Bi₂O₃ particles have a more homogeneous distribution within the samples than microscale Bi₂O₃ particles. The shielding parameters of the proposed mortars were measured using the HPGe detector at various γ-ray energies emitted by standard radioactive point sources ²⁴¹Am, ¹³³Ba, ⁶⁰Co, ¹³⁷Cs, and ¹⁵²Eu. The experimental values of the prepared mortars’ mass attenuation coefficients (MAC) match well with those determined theoretically from the XCOM database. Other shielding parameters, including half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective electron density (N_eff), effective atomic number (Z_eff), equivalent atomic number (Z_eq), and exposure buildup factor (EBF), were also determined at different photon energies to provide more shielding information about the penetration of gamma radiation into the selected mortars. The obtained results indicated that the sample containing 30% by weight of nano Bi₂O₃ has the largest attenuation coefficient value. Furthermore, the results show that the sample with a high concentration of Bi₂O₃ has the highest equivalent atomic numbers and the lowest HVL, TVL, MFP, and EBF values. Finally, it can be concluded that Bi₂O₃ nanoparticles have higher efficiency and protection compared to microparticles, especially at lower gamma-ray energies. Full article

In the current study, the gamma-radiation-shielding characteristics of novel gypsum–lime–waste marble-based mortars reinforced with micro-PbO and nano-PbO powders were investigated. In total, seven mortar groups, including a control mortar (named GLM), were prepared. The other groups contained10, 20, and 30 wt.% of both micro-PbO and nano-PbO as a waste marble replacement. This study aimed to explore the effect of particle size and concentrations of PbO powders on the γ-ray-shielding capability of GLM mortars. For this purpose, an HPGe detector and five standard radioactive point sources (²⁴¹Am, ¹³³Ba, ¹³⁷Cs, ⁶⁰Co, and ¹⁵²Eu) were employed to measure different shielding parameters, including the linear attenuation coefficient (μ), mass attenuation coefficient (μ_m), mean free path (MFP), half-value layer (HVL), and tenth-value layer (TVL), for the prepared samples in the energy range between 59.53 keV to 1408.01 keV. On the basis of μ_m values, other significant shielding parameters such as effective atomic number (Z_eff), effective electron density (N_eff), equivalent atomic number (Z_eq), and exposure buildup factor (EBF) were also computed to explore the potential usage of the proposed mortars as radiation protective materials. The results reported that the smallest HVL, TVL, and MPF, as well as the largest attenuation values, were obtained for mortars reinforced by nano-PbO compared to those containing micro-PbO. It can be concluded from the results that the mortar samples containing nano-PbO had a remarkably improved gamma-radiation-shielding ability. Thus, these mortars can be used for radiation shielding on walls in nuclear facilities to reduce the transmitted radiation dose. Full article

The specific activity and spatial distribution of ²³⁸U, ²³²Th and ⁴⁰K were determined in the surface soil from the Lișava uranium mining sector. This sector belongs to the Banat district, an historically important uranium mining area in Romania (an area with closed uranium mines and a radioactive waste dump). Gamma-ray spectrometry using a high-purity germanium (HPGe) detector was used to measure the activity of naturally occurring radionuclides in the soil. The average specific activities of ²³⁸U, ²³²Th and ⁴⁰K in the soil were 197.21 Bq/kg for ²³⁸U, 16.21 Bq/kg for ²³²Th and 543.21 Bq/kg for ⁴⁰K. The mineral contents of selected waste rock samples (sandstones) were examined using a scanning electron microscope (SEM), which revealed that brannerite, pitchblende and coffinite were the most important uranium-bearing minerals. The means of the radiological hazard parameters were calculated to be 262.22 Bq/kg radium equivalent activity (Raeq), 123.72 nGy/h absorbed gamma dose rates (DR), 0.7 external hazard index (Hex) and 1.8 representative level index (RLI). The spatial distribution of the risk assessment indices associated with the investigated soils exceeded the median values provided by UNSCEAR and reflected the geological settings and influences of anthropic activities such as uranium mining practices and the tipping of radioactive mining waste. Full article

We have attempted to develop the gamma radiation shielding abilities of newly prepared epoxy composites by introducing ZrO₂. The radiation shielding parameters are experimentally reported below. The experimental setup included an HPGe detector and different radioactive point sources which emitted photons with energies of 0.06, 0.662, 1.173, and 1.333 MeV. The gamma radiation shielding abilities of the epoxy composites were examined in the context of the linear attenuation coefficient (LAC), half-value layer (HVL), radiation absorption ratio, and other factors. The experimental and Phy-X results for the LAC were compared, and acceptable consistency was reported. The lowest LAC values were reported for EBZr-0 (free of ZrO₂), and we found that the photon attenuation competence of the present epoxy improved as a result of increasing the ZrO₂ content. We compared the LAC values for the present epoxy composites with other samples, and we found that the prepared composites with 20% to 40% ZrO₂ had higher LAC values than epoxy with 30% Yahyali Stone. The HVL lengths of the epoxy composites reduced with the addition of ZrO₂ for the four selected energies, which confirmed that introducing ZrO₂ improves the radiation absorption abilities of epoxy composites. At 0.06 MeV, the HVL for the ZrO₂-free epoxy was 2.60 cm, which fell to 0.23 cm after adding 40% ZrO₂. The mean free path (MFP) for the prepared composites was less than 1 cm at 0.06 MeV (standard for EBZr-0), while it was 1.32 cm for EBZr-10. For the other energies, it was higher than 6 cm, and became higher than 10 cm at 1.333 MeV for all composites. The obtained results suggest that non-toxic, natural, and cheap epoxy composites with high ZrO₂ content have the potential to improve the gamma ray shielding competence of epoxy composites for low energy radiation applications. Full article

The work aimed to show the applicability of geological studies to the investigation of radiation risk assessment due to the presence of naturally occurring radionuclides of terrestrial origin in the soil. Soil samples were taken from a Tatra Mountains area for which geological maps were available. The concentration of selected radionuclides incl. ⁴⁰K, ²³⁸U and ²³²Th was determined by gamma-ray spectrometry with a HPGe-detector. Radioactivities and calculated absorbed dose rates were co-related to complex bedrock matrices based on an original methodology. The correlations were proved by performing a Principal Component Analysis (PCA). The rocks that had a significant impact on the rate of absorbed dose from the soil were strongly related to the radioactivity of the uranium series. The share of the following fractions was the most significant: granite with pegmatite, gneiss, granitoid and gneiss, coquina, marl and glauconite, hard limestone, dolomite and limestone. The rock types additionally showed good correlation with radioisotopes from the thorium series. Granitoids with potassium feldspar, on the other hand, contributed the largest share of ⁴⁰K radioisotope content. Full article

The present investigation was aimed at the utilization of alternate materials, emphasizing hazardous industrial products (red mud and cathode ray tubes), as constituents of radiation shielding concrete. The usage of these hazardous industrial products improves the sustainability and performance of the radiation shielding concrete. Five concrete blocks were cast and their density, compressive strength, gamma shielding factors, radiation absorption ratio, and transmission factor were explored. For this purpose, gamma-ray shielding measurements were done with the help of an HPGe detector. Mix-1, with zero contents of red mud and CRTs, had the lowest LAC. The LAC results demonstrated that the shielding performance of the current concretes would be better with the increase in red mud and cathode ray tube glass. The Transmission factor (TF) for the prepared concretes with a thickness of 2 cm varied between 11.9–26.1% at 0.06 MeV, while it varied between 4–13% for a thickness of 3 cm. The TF results showed that the composites with a thickness of 2, 3, or 5 cm are good shields against lower energy radiation. The radiation absorption ratio (RAR) for the prepared concretes is high at low energy, suggesting that these new composites can absorb most of the low-energy photons. The RAR results emphasize that the increase in CRTs in the new composites enhanced the radiation shielding features, and when the CRT glass is at a maximum, more attenuation was achieved. Full article